1. Field of the Invention
This invention relates to an improved equipment useful for winning of ores, particularly coal in longwall mining.
2. Description of the Prior Art
Longwall mining is the most efficient and globally practised underground method of winning coal, which offers possibility of complete automation. Gradually, over the years there has been consistent effort to reduce the manpower deployed at a longwall face. In fact, any device can be made fully automatic only when the whole operation involved is machine dependent using practically no manpower. With the present longwall mechanisation system available, only the face machine system can be made automatic as the face operations are fully mechanised, but at the same time it involves many other functions in gateroads, most of which are manually operated, and therefore, become hindrance to the further automation of the system.
Here the existing equipment for longwall mining is illustrated with reference to FIG. 1 of the drawings accompanying this specification. There are two sets of master chock shield (1) and slave chock shield (2) at the two rear ends of longwall face equipment with general chock shields within them along the face. In front of the chock shields there is an armoured face conveyor (3) along the face which has got two sigma sections on both sides of it over which a shearer (4) is movably installed. Shearer cuts coal and loads automatically to the armoured face conveyor (hereinafter called AFC) (5). At the discharge end of AFC (5) there is another armoured conveyor at the right angle along gate road, which is called Bridge Stage Loader (hereinafter called BSL) (6). One BSL (6) is elevated like a bridge. At the discharge end of BSL there is a belt conveyor along gate road in the same line which is called gate belt conveyor (GBC) (7) which discharges to trunk belt conveyor (not shown). There are unit vertical supports (not shown) upto 30 meters ahead of working face. There is a rail line (9) along the gate road beside the gate belt conveyor.
Longwall method involves the following operations as practised commonly--(a) cutting of coal by shearer or by plough (b) conveying coal from face by AFC, (c) crushing of coal to size, (d) conveying coal from armored face conveyor to trunk belt conveyor by bridge stage loader and from there to out-bye system (e) supporting the face, (f) supporting gateroads, (g) shifting of bridge stage loader and power pack (h) dismantling of rails, (i) tensioning arrangement and shifting of belt intake (low height) structure and (j) belt shortening at intervals. Out of the above functions, some are totally and some are partially dependent on manual operations.
Most important of them is the supporting of gateroads. The bolted roof of the gateroads are supported by unit vertical supports (mainly by hydraulic props) by rows either individually or along with girders (24) as goal post support, generally upto a distance of 30 m in front of the face, as a norm being directed by Director General of Mines Safety (India). The operations of installation of props with proper setting load and withdrawal of the same are mostly manual functions. A crusher (10) is mounted over the BSL for sizing coal suitable for belt conveyor. This BSL requires supervision at both the ends and also at the crushing point. The vital point is that it has to be advanced for every cut of coal face which is mostly a manual operation with the help of a double acting ram and hydraulic props tightly set along the gateroads.
The power pack (11) for hydraulic power supply and Gate End Boxes (12) for electrical power supply are generally mounted over rails so it is necessary to maintain the rail line laid over wooden sleepers upto a few meters ahead of the face along the main gateroad (25). Shifting of power packs is a cumbersome process which involves additional unskilled manpower for the operation. Thus, it is clear that there are many operations in a longwall method which are still dependent on manual labour.